Carboniferous Rock Mass Permeability Studies in Underground Mine of the Upper Silesian Coal Basin in Poland
Niedbalska, Katarzyna; Bukowski, Przemysław; Augustyniak, Iwona
Central Mining Institute, Poland
Active and flooded mines in Poland coexist. Due to this fact, active and flooded mines share conditions that lead to the occurrence of hazards related to the accumulation and flow of water and gas in the rock mass. This often determines the level of the water hazard and the possibility of the occurrence of a methane hazard for both active mines and the surface. Increasingly deeper mining results in increasingly lower water inflows to the workings, but in turn leads to increasingly higher emissions of methane. One of the reasons for the difficulty in determining the conditions of water and gas circulation in the workings and the rock mass as well as the difficulty in rock mass water and methane drainage planning is often the lack of knowledge regarding the permeability of the rocks and the rock mass in the vertical profile.
Commonly employed methods of cohesive rock permeability studies are applied to specifically prepared (extracted) rock samples, studied in one direction. Such standard studies make it possible to obtain results by at least one order of magnitude smaller than in the case of studies conducted perpendicularly to the core axis and parallel to the rock bedding. The study result is obtained in a time-consuming manner, following the preparation of a drill core and the selection of samples. It also reproduces the filtration process, which is closer to the process of seepage between strata. The article characterises the study process for filtration ratio profiling for flow directions x, y, z using the Micrometrics PDPK-400 apparatus, as well as its advantages and disadvantages.
The possibility to compare the results of studies conducted using a rock permeability profilometer with study results obtained via other methods was indicated as well. As for particular applications in underground mines, the possibility was suggested to use them in the forecasting of water and gas flows through the pillars and body of coal in the rock mass during the flooding of a decommissioned mine, and also in mine water drainage planning and the opening out of remaining deposits in originally flooded mines.
Possible applications in hydrogeology were suggested, particularly in the water hazard evaluation of mines situated close to the reservoirs of flooded mines, in fire prevention in coal mines and in the determination of zones with increased permeability, e.g. for mine gas migrations.